The following interesting question arose yesterday from what at first appeared to be some petty Twitter bickering: who was the worst president for civil liberties in US history? That question is a difficult one to answer because it is so reliant upon which of many valid standards of measurement one chooses; it depends at least as much on the specific rights which one understands the phrase "civil liberties" to encompass. That makes the question irresolvable in any definitive way, but its examination is nonetheless valuable for the light it sheds on current political disputes.

It's worthwhile first to set forth the context in which the question arose. At their Lawfare blog, Ritika Singh and Benjamin Wittes posted an excerpt of an essay they wrote for a new book on the War of 1812; their essay pertains to the impact of that war on civil liberties and executive power. The two Brookings writers note that despite intense domestic opposition to the war, President Madison "eschewed the authority to detain American citizens in military custody or try them in military tribunals, and more generally, declined to undertake the sorts of executive overreaches we have come to expect - and even encourage - from our presidents in war."

After Julian Sanchez, I and others tweeted that essay by remarking that Madison refrained from exploiting the war to abridge civil liberties, Slate's Matt Yglesias' wrote:

guardian.co.uk

That struck me as a cheap and vapid reply. Nobody was suggesting that Madison was the personification of civil liberties nirvana. Rather, the point was a very narrow and discrete one: he largely refrained from exploiting the War of 1812 as a pretext for abridging extant political rights. Whether he owned slaves - or was otherwise the worst monster in history - does not remotely pertain to, let alone negate, that specific and important historical fact about Madison's presidency.

Moreover, the issue raised by the essay on Madison was about the extent to which presidents use their power to erode civil liberties which exist when they assumed the office, or refrain from attacking those rights despite having the opportunity in the form of war or other crises. That a person is born into a society in which the evil of slavery already exists has little to do with that historical question.

That said, once one posits a president's personal slavery ownership as inconsistent with a positive civil liberties record - as Yglesias implicitly did - then that must be the number one factor in assessing a president's place on the civil liberties list. By that metric, all slave-owning presidents, or one who expressly endorsed the Dred Scott decision as James Buchanan did, would automatically have to be deemed the worst.

After all, owning human beings as chattel is the supreme civil liberties violation, by far the gravest civil liberties abuse in US history. That goes without saying. It is sui generis.

That's why it was so bizarre to see that the very same Matt Yglesias, just moments later, pronounced Woodrow Wilson - a president who never owned any slaves and never presided over slavery - to be the "worst-ever president on civil liberties", even suggesting that Wilson has no "serious competition" for that ignominious title. It was when I pointed out the irony of Yglesias' selection of a non-slave-owning president in light of his tweet that the interesting question arose of who should be considered the worst civil liberties president in US history.

If one were simply to consider specific acts which constituted grave assaults on civil liberties - narrowly defined as the core political rights explicitly protected by the Bill of Rights: free speech, freedom from deprivation of life and liberty without due process, etc. - one could make a strong argument for several presidents. John Adams signed The Alien and Sedition Acts, which essentially criminalized certain forms of government criticism in preparation for a war with France, a radical assault on the First Amendment.

And then there are the two War on Terror presidents. George Bush seized on the 9/11 attack to usher in radical new surveillance and detention powers in the PATRIOT ACT, spied for years on the communications of US citizens without the warrants required by law, and claimed the power to indefinitely imprison even US citizens without charges in military brigs.

His successor, Barack Obama, went further by claiming the power not merely to detain citizens without judicial review but to assassinate them (about which the New York Times said: "It is extremely rare, if not unprecedented, for an American to be approved for targeted killing"). He has waged an unprecedented war on whistleblowers, dusting off Wilson's Espionage Act of 1917 to prosecute more then double the number of whistleblowers than all prior presidents combined. And he has draped his actions with at least as much secrecy, if not more so, than any president in US history.

Ultimately, it is close to impossible to rank these abuses strictly as a qualitative matter, in terms of the powers seized. How does one say that interning citizens in concentration camps (Roosevelt) is better or worse than imprisoning people for dissent (Adams and Wilson), putting people in cages with no charges (Lincoln, Bush, Obama), or claiming the power to execute citizens in total secrecy and without any checks of any kind (Obama)? If anything, one could reasonably argue that the power of due-process-free executions is the most menacing since it's the only act that is permanent and irreversible.

Moreover, it is one of the ironies of US history that civil liberties erosions are often accompanied by civil liberties progress from the same leader: Adams was integral in the founding of the republic and its rights-enshrining documents; Lincoln freed the slaves; Wilson supported women's suffrage; Roosevelt appointed two of the most sterling civil liberties advocates to the supreme court; Obama withdrew authorization for some torture techniques (ones that were not in use when he was inaugurated) and banned CIA black sites (ones that were empty when he assumed office).

Ultimately, there are two critical factors that, for me at least, are highly influential if not decisive in determining the proper ranking. The first is the extent to which the civil liberties abuses are temporary or permanent.

Most of the contenders for worst civil liberties abuses were "justified" by traditional wars that had a finite end and thus dissipated once the wars were over. Lincoln's habeas suspension did not survive the end of the Civil War, nor did FDR's internment camps survive the end of World War II. The Alien and Sedition Acts were severely diluted fairly quickly, while the bulk of Wilson's abuses which survived World War I lay dormant until the War on Terror. As horrible as they were, these radical erosions were often finite, arguably by design, since the wars which served as their pretext would foreseeably end at some point.

This is one key factor that distinguishes the War on Terror. By its nature, it will never end, at least not in the foreseeable future. It is a "war" far more in a metaphorical sense than a real one.

Since it began, both administrations who have waged it have expressly acknowledged its virtually indefinite - and thus unique - nature. In May 2009, when Obama unveiled his proposal for "preventive detention", he said: "Unlike the Civil War or World War II, we can't count on a surrender ceremony to bring this journey to an end." He added that we'll still be fighting this war "a year from now, five years from now, and - in all probability - 10 years from now."

Just last week, the Washington Post reported that the Obama administration is creating permanent bureaucratic systems to implement its War on Terror powers as it "expects to continue adding names to kill or capture lists for years". Specifically, "among senior Obama administration officials, there is broad consensus that such operations are likely to be extended at least another decade." That "suggests that the United States has reached only the midpoint of what was once known as the global war on terrorism."

Civil liberties abuses justified by a finite war can be awful while they last, but then they cease. Abuses that are systematized based on the premise that they are to be permanent do far more than that: they radically alter the nature of the government and the relationship of the political class to the citizenry.

This, to me, has always been the most uniquely pernicious aspect of the War on Terror civil liberties assaults of the last decade: they will not end when the "war" does because the "war" will have no end. Each new power is embedded permanently into the political framework, incrementally transforming the political culture and the species of government itself.

The second vital factor is the justification used for these assaults. However critical one wants to be of Lincoln, Wilson and Roosevelt - and harsh criticism is appropriate in all three cases - they were actually fighting major wars that had the potential to severely harm if not destroy the US. To the extent that war is a justification for increasing the powers of the executive, those three wars are clearly the most compelling examples.

By contrast, the "War on Terror" is not even legitimately described as a "war", let alone one anywhere near the magnitude of its predecessors. Shortly after I began writing about politics in late 2005, I examined the inane tactic of Bush-following neoconservatives - one that is, like so many neocon views, now vigorously embraced by many Obama defenders - to cite Lincoln's civil liberties abridgments during the Civil War to justify abridgments in the name of the War on Terror. The fundamental differences are obvious:

"During Lincoln's Presidency, the entire nation was engulfed in an internal, all-out war. Half of the country was fully devoted to the destruction of the other half. The existence of the nation was very much in doubt. Americans were dying violent deaths every day at a staggering rate. One million American were wounded and a half-million Americans died (a total which represented 5% of the total population), making it the deadliest war America has ever faced, by far, including all wars through the present. On multiple occasions, more than 25,000 Americans – and sometimes as many as 50,000 – were killed in battles lasting no more than three days. The scope of carnage, killing, and chaos – all within the country, on American soil – is difficult to comprehend.

"Making matters worse – much worse – the country was only 70 years old at the time. And even before the Civil War began, America was teetering precariously from these unresolved internal conflicts. The country then was a shadow of what it is today, with a tiny faction of the strength, stability and cohesion which, 140 years later, characterize the United States."

It takes little effort to demonstrate that the "War on Terror" is not in the same universe. As Professor Richard Jackson has documented, there is a greater risk of dying from lightning strikes or bathtub falls than terrorism. Professors John Mueller and Mark G. Stewart, writing in the latest issue of International Security, condemned the "extraordinarily exaggerated and essentially delusional response" to 9/11. As Professor Stephen Walt described their article:

"Mueller and Stewart analyze 50 cases of supposed 'Islamic terrorist plots' against the United States, and show how virtually all of the perpetrators were (in their words) 'incompetent, ineffective, unintelligent, idiotic, ignorant, unorganized, misguided, muddled, amateurish, dopey, unrealistic, moronic, irrational and foolish.' They quote former Glenn Carle, former deputy national intelligence officer for transnational threats saying 'we must see jihadists for the small, lethal, disjointed and miserable opponents that they are,' noting further that al-Qaida's 'capabilities are far inferior to its desires.'"

To the extent the validity of the proffered justification matters, and it must matter some, the War on Terror abuses are easily the worst for this metric. Unlike the actual, threatening wars of the past, this "war" is pure pretext, a total farce: so out of proportion to the civil liberties assaults employed in its name as to be inconceivable.

As noted, this discussion assumes a rather narrow range of the term "civil liberties": namely a focus on the original core political liberties expressly guaranteed by the Bill of Rights: freedom of speech, freedom from deprivation of life and liberty without due process, habeas corpus. If one expands the term to include more contemporary debates surrounding issues such as gay equality and reproductive rights, as is proper, then the overall picture meaningfully changes.

The one common strain running through these historic civil liberties assaults is war. War almost always erodes political liberties. That has always been true. Cicero famously observed "inter arma, enim silent leges" (in times of war, the law falls mute).

That fact - that wars maximize a political leader's power - is a key reason they often crave war and why wars, under the Constitution, were supposed to be extremely difficult for presidents to start. As John Jay wrote in Federalist 4, "absolute monarchs will often make war when their nations are to get nothing by it, but for the purposes and objects merely personal" (that's also why the absurd contortions invoked by President Obama to fight a war in Libya not only in the absence of Congressional approval, but in the face of formal Congressional disapproval, belongs high on the list of his worst and likely most enduring civil liberties assaults).

But in terms of the role played by war in enabling civil liberties assaults, at least the exploited wars are usually real. In the case of the "War on Terror", it is far more illusory and frivolous than real. That - along with their permanence - is a major factor in determining where the civil liberties erosions of the last decade, and the presidents responsible for them, rank in history.